1. Field of the Invention
This invention relates to semiconductor device processing and, more particularly, to the processing of devices containing silicon.
2. Art Background
A major source of silicon device failure results from introduction of contaminants during the fabrication process. This contamination often occurs between fabrication steps when the sample must be transferred from one deposition apparatus to another, or when an apparatus is vented to the atmosphere in order to prepare for a subsequent processing step. During the transfer between equipment or during the period when the equipment is vented, impurities inevitably in the atmosphere contaminate the surface of the sample. These impurities are trapped between device layers upon deposition of subsequently fabricated layers.
The problem of contamination is particularly acute in devices, such as MOS IGFETs and MOS capacitors that contain a silicon dioxide/polycrystalline silicon interface. Generally, the silicon dioxide is formed by oxidizing a silicon substrate. The substrate is then transferred to chemical vapor deposition (CVD) equipment for deposition of polycrystalline silicon from a silane (SiH.sub.4) containing reactant mixture. (See, for example, M. E. Cowher and T. O. Sedgwick, Journal of the Electrochemical Society, 119, 1565 (1972).) Thus, for devices requiring a silicon dioxide/polycrystalline silicon interface, there is an increased opportunity for device contamination with its associated difficulties.